Embodiments of the inventive concept relate generally to electronic data storage devices. More particularly, embodiments of the inventive concept relate to solid state drives and related methods of operation.
A number of modern data storage systems incorporate flash memory devices to perform a variety of functions. Solid state drives (SSDs) constitute one such system. SSDs are now used, for instance, as replacements for hard disk drives (HDDs) in personal computers and other platforms. Such solid state drives are typically designed to incorporate large amounts of flash memory for mass data storage.
One notable shortcoming of flash memory devices is their inability to perform data overwrite operations. In particular, a region of a flash memory device cannot be programmed until any current data is removed from the region. Accordingly, a block erase operation may be required before a program operation can be performed on the region.
Flash memories are also limited in the number of times that each region can be programmed and erased before wearing out. Accordingly, in an effort to equalize the lifetimes of different regions, wear-leveling operations can be performed to move data to different regions in conjunction with new program or erase operations.
Flash memories can also be susceptible to inefficient use of memory space due to their inability to perform data overwrite operations. Accordingly, periodic merge or move operations may be used to consolidate data from physical blocks having significant numbers of invalid pages or fragmented use of space. Additionally, garbage collection operations may also be required to eliminate unused or invalid data.
Operations such as block erase operations, wear-leveling operations, merge or move operations, and garbage collection operations can delay execution of memory access operations, such as read and program operations. Accordingly, they can reduce the response time and overall performance of flash memory devices such as those used in SSDs.